A top Two Sigma investment executive has taken leave from the firm amid a series of challenges for the hedge fund giant

• A Two Sigma chief investment officer has taken a medical leave, Insider has learned.
• The firm announced the leave of Alex Ginsburg, CIO of equities, to investors and employees in July.
• The fund is also grappling with governance and management issues related to its feuding founders.

Insider has learned that a senior Two Sigma investment executive has taken a leave of absence from the firm.

According to people familiar with the situation, Alex Ginsburg, a 21-year company veteran and chief investment officer for equities research, has stepped down from his role at the hedge fund to take a medical leave.

According to people familiar with the matter, the company informed investors of the executive’s departure and announced it internally in mid-July, along with other personnel changes such as the appointment of Jeff Penney and Timothy Reynolds as interim co-chief operating officers.

Ali-Milan Nekmouche, chief data strategist at Two Sigma since 2004, has been named as Ginsburg’s replacement. A spokesperson for Two Sigma declined to say who would take over for Nekmouche.

Ginsburg’s departure is the latest complication for the firm, following public disclosures of an acrimonious feud between Two Sigma founders David Siegel and John Overdeck.

Two Sigma warned investors in a March securities filing about the risks posed to the company by its feuding founders and their inability to agree on critical business matters. Siegel and Overdeck have been at odds for years over the direction of the $60 billion quant trading firm, including disagreements about corporate governance, succession plans, defining top executives’ roles, and team organization.

According to the company, the infighting is threatening recruiting, retention, and employees’ ability to do their jobs.

According to people familiar with the situation, in 2022, a group of executives, including Ginsburg and Geoffrey Duncombe, another chief investment officer, “threatened to resign if Siegel didn’t step back at the firm,” according to the Wall Street Journal. According to the Journal, Siegel did not leave the firm, and the group ended up staying at Two Sigma.